Anything from here
I tend to make up my own using OS maps.
But it all depends on your fitness, ability and weather.
All of the bike shops have pre-printed maps of the best/classic routes.
Starting from the south, Wheelbase, Biketreks, Keswick mountain bikes and maybe Evans in Kendal. Drop into any of these shops with a map and they should be able to advise or sell you their maps for a couple of pounds.
Google all of the above........................
Various Skidaw routes
Across the other side of the M6 you have the Howgills, Bowderdale, the Calf, High Cup Nick and Cross Fell for mega all day rides.
Endless routes if you can read a map